ARPA Explained: The Archaeological Resources Protection Act for Detectorists, Rockhounds and Collectors

The Archaeological Resources Protection Act of 1979 (ARPA, 16 U.S.C. §§ 470aa–470mm) is the federal law behind most "don't take artifacts" warnings on public land. It applies to two kinds of land: public lands, meaning land the United States owns in fee (national parks, national wildlife refuges, national forests, BLM land and other federal land, but not the Outer Continental Shelf or Smithsonian land), and Indian lands held in trust or restricted by the United States (16 U.S.C. § 470bb(3), (4)). It doesn't apply to state, county, city or private land. Those have their own laws, such as Florida's Chapter 267 and the Texas Antiquities Code.

On that land, no one may "excavate, remove, damage, or otherwise alter or deface" an archaeological resource without a permit (§ 470ee(a)). Permits go only to qualified applicants working "for the purpose of furthering archaeological knowledge in the public interest," and everything they recover stays federal property in a museum or university (§ 470cc(b)). There is no ARPA permit for hobby collecting.

Why the age line isn't the whole story

ARPA's 100-year floor is the federal minimum, not the only rule. The Forest Service's own prohibition covers any "prehistoric, historic, or archaeological" artifact with no age threshold (36 CFR 261.9(g), (h)), and BLM's covers any "cultural, archaeological or historic resource" (43 CFR 8365.1-5(a)(1)). National parks ban removing nearly everything (36 CFR 2.1). States set their own lines: North Carolina's state ARPA protects resources at least 50 years old on state land, and Florida State Parks treats anything over 50 years old as historic. Treat any old, human-made object on public land as protected until the land manager tells you otherwise.

What ARPA means for each hobby

Metal detecting. BLM's rules let you use a metal detector to collect the rocks and minerals you're allowed to take (43 CFR 8365.1-5(a)(3)), and ARPA doesn't reach a stray modern coin. But detecting near a historic site — a homestead, a camp, a stage stop, a battlefield — puts you squarely in ARPA territory, because everything there is part of the site. National park units ban detectors outright (Cape Hatteras, Padre Island).

Rockhounding. Obsidian, chert, jasper and agate are rocks, but a flake or point made from them by people is an artifact. Central Oregon's obsidian fields show why: Glass Buttes was a major quarry for thousands of years, so a piece with a worked edge must stay where it is. In Arizona, the Quartzsite desert and the Vulture Mine area carry the same warning (see our BLM collecting guide).

Fossil hunting. Fossils fall under the Paleontological Resources Preservation Act, not ARPA (PRPA explained), unless they're part of an archaeological site, for example a bone tool. Where a fossil locality also holds cultural material, as in the coulees around Judith Landing, both laws apply.

Magnet fishing and beachcombing. ARPA covers portions of shipwrecks on federal land, including federally owned lakebeds. Corps of Engineers lakes are often federal land, so historic material there is governed by federal rules, not the state's (Lake Texoma). On most beaches, the state's own antiquities law is the one that decides what you can keep.